When I announced that I might be interested in checking out double stars, James bought The Cambridge Double Star Atlas, by James Mullaney and Wil Tirion, for me. It’s a big book – larger than A4 – although only 148 pages long. It’s spiral bound, meaning that despite its size it’s quite useable: you’re not forced to to deal with an A3 map on your lap while at the eye piece. The paper seems to be good quality and slightly waxy; I’ve had mine sitting on dewy grass and although some of the pages have slight ripples in them now, the book itself hasn’t suffered at all. And it’s got wonderful content, with an excellent introduction and superb maps.
In the introduction, Mullaney takes the reader – anyone from a novice to expert – through the process of making the book itself, then tabulates the codes that are used to signal the discoverer and/or catalogue used when discussing individuals pairs/systems. There is an excellent section on the practicalities of observing – useful not just for doubles hunting – explaining how to train the eye to observe, as well as the impact of sky conditions and the resolution and magnification of telescopes. He also discusses the idea of record-keeping, and it was from reading this that I decided to keep a journal of my observations.
Before getting to the maps, Mullaney has a list of 133 ‘showpiece’ double and multiple stars. As well as giving the name of the object, its coordinates and magnitude, he includes a short and usually evocative description of each object. For those of us who like lists, this is something akin to having a Messier list for double/multiples. It’s a fabulous challenge (although disappointingly for me a fair number are beyond my viewing range, here at 37 degrees south).
The heart of the book is the 30 double-page maps that cover the entire sky (p1 is the North Celestial Pole, p30 the South). The maps show about 900 non-stellar objects as well as the doubles, so it can make an excellent all-round atlas too. The stars making up constellations are connected by faint blue lines, and the ‘spheres of influence’ of the constellations is also shown, which is useful when trying to locate specific objects. The doubles that are specifically listed objects (all 25,000 of them) are labelled in green, making them easier to read under red light. I’ve never been especially good with maps, but these are easy to read and easy to use, both while planning an observation session and while at the telescope.
Finally, there are the Appendices. App A lists the constellations and which pages they appear on; B has the ever-useful table of Greek letters. But C is where the money really is: a list, in order of RA, of the doubles Mullaney specified be in the Atlas. The table has the object’s designation, RA and Dec, magnitude, and the pair’s separation, as well as occasional helpful remarks (this is Antares, this is in the middle of the Pleiades). This appendix can be used to give the astronomer a better idea of exactly what she is looking at on the map; when used in conjunction with an Argo, if a random double is spotted it can be looked up via the RA/Dec to see whether it is listed and if so its name.
Would I buy this Atlas again (or get James to buy it)? In a heartbeat. Of immense value to anyone who is interested in looking at double stars. It’s easy to use, lovely to flick through when planning, and sturdy into the bargain.